This invention relates to an image formation apparatus and, more particularly to an image formation apparatus having a page memory whose memory capacity is at least one page of A4 size paper (approximately 16 MB), and capable of including a document feeder.
In copying process in a conventional full-color electrophotographic copier, originals are placed on a rotational document feeder (RDF), face up, and supplied one by one to an original table where each original is placed face down. An optical scanning unit scans in a direction (the positive sub-scanning direction: forwarding direction) at a predetermined speed to read an original. A low scanning speed is preferable, if the time that a CCD (Charge Coupled Device) accumulates charge corresponding to lights reflected from the original is considered. On the other hand, in order to increase the entire processing speed of the full-color electrophotographic copier, the returning speed of the optical scanning unit to the home position in the sub-scanning direction needs to be increased.
The structure of the conventional technique is such that an optical scanning unit reads an original by irradiating the original only when scanning in the positive sub-scanning direction. With such structure, when a plurality of original documents are consecutively duplicated by using the RDF, resonance may occur in the entire apparatus due to the long drive time of the driving motor of the optical scanning unit to return to the home position at a high speed.
In order to solve the above problems, even if the original is read in both directions of the sub-scanning direction, since the CCD can read the image only from the positive direction of the main scanning direction, the original read during the returning processing in the sub-scanning direction is a mirror image with respect to the original read in the forwarding processing.